Gas fired heating installation

ABSTRACT

A gas fired heating installation in which several gas heater assemblies communicate with a common flue on different levels for drawing air of combustion from the flue and discharging combustion gases into the flue is equipped with a thermostatically controlled throttling valve in the intake duct of each heater assembly. As the temperature of the gas entering the assembly rises because of operation of a heater on a lower level, the throttle valve increases the flow section of the intake duct so that the gas, partly stripped of its oxygen by the lower heater, enters the higher heater in greater volume to provide an amount of oxygen approximately independent of the number of operating heaters.

United States Patent 1 Diermayer et al.

[4 1 Feb. 18, 1975 GAS FIRED HEATING INSTALLATION [73] Assignees: Luitpold Kutzner, Munich,

Germany; Werner Diermayer, Lafayette, Calif. part interest to each 22 Filed: Feb. 5, 1974 [2]] Appl. No.: 440,061

[30] Foreign Application Priority Data Feb 26, 1973 Germany 2309540 [52] US. Cl 126/112, l26/77, 126/290 [51] Int. Cl. F24h 3/00 [58] Field of Search 126/77, 80, 112,285 R, 1215/289,;90;,236/ 1 o, 16/96; 237/50, 55

[56] References Cited UNITED STATES PATENTS 3,228,605 l/l966 Diermayer et al 126/285 Rcxer 236/96 Diermayer et al. 236/l0l Primary Examiner-Carroll B. Dority, Jr. Attorney, Agent, or FirmHans Berman [5 7] ABSTRACT A gas fired heating installation in which several gas heater assemblies communicate with a common flue on different levels for drawing air of combustion from the flue and discharging combustion gases into the flue is equipped with a thermostatically controlled throttling valve in the intake duct of each heater assembly. As the temperature of the gas entering the assembly rises because of operation of a heater on a lower level, the throttle valve increases the flow section of the intake duct so that the gas, partly stripped of its oxygen by the lower heater, enters the higher heater in greater volume to provide an amount of oxygen approximately independent of the number of operating heaters.

6 Claims, 2 Drawing Figures GAS FIRED HEATING INSTALLATION This invention relates to gas fired heating installations, and particularly to an installation in which a plurality of gas fired heaters are connected to a common flue on different levels to receive air of combustion from the flue and to discharge their combustion gases into the flue.

Except for the lowermost heater, the several heater assemblies, when simultaneously operated, receive from the flue a mixture of air and of combustion products whose oxygen content varies with the number of lower, simultaneously operating heaters. The efficiency of gas heaters depends on an adequate amount of oxygen being supplied for full combustion of the gaseous fuel while avoiding an excess of non-flammable material which merelycarries heat into the flue. Conventional, gas fired heating installations of the type described are necessarily designed for most economical fuel use when a fixed number of heaters is in operation while wasting fuel and/or supplying less than an optimum amount of thermal energy under all other conditions.

It is a primary object of this invention to provide a heating installation of the type described with automatic controls which vary the amount of oxygenbearing gas supplied to each heating assembly in accordance with the oxygen content of the gas, that is, the number of heaters operating on lower levels.

With this object and others in view, the invention provides the intake of each heater assembly with a flow control device for controlling the flow of gas from the flue to the burner and responsive to operation of a heater on a lower level for increasing the flow section of the intake, and responsive to interruption of operation of the lower heater for reducing the flow section of the intake.

In another aspect, the invention provides a method of controlling the operation of a gas heater in which a gaseous fuel and an oxygen-bearing gas are fed to the heater, the temperature of the gas is sensed, and the rate of flow of the oxygen-bearing gas is controlled in response to the sensed temperature.

Other features, additional objects, and many of the attendant advantages of this invention will readily be appreciated as the same becomes better understood from the following detailed description of a preferred embodiment when considered in connection with the appended drawing in which:

FIG. 1 shows a heating installation of the invention in fragmentary elevation, portions being broken away to reveal internal structure; and

FIG. 2 shows an element of the device of FIG. 1 in section on the line II II on a larger scale.

Referring initially to FIG. 1, there is shown only as much of a heating installation according to the invention as is needed for its understanding. A flue passes vertically upward through the several floors of a building in which it is desired to heat each floor individually, natural gas being the preferred fuel. An opening 11 at the bottom of the flue 10 admits air of combustion for the individual heater assemblies on respective upper floors, only two identical heater assemblies being shown.

Each heater assembly includes a branch conduit 12 which is approximately U-shaped in a vertical plane. The enlarged central portion 16 of the conduit 12 receives gaseous fuel from a supply line 13 which leads to a gas burner 14 in the conduit portion 16. Water tubes 15 arranged above the burner 14 receive much of the thermal energy of the burning gas and supply hot water to all radiators on a floor in a conventional manner, not shown.

Each heater assembly is sealed from the open space of the floor on which it is located. Aside from unintentional leaks, the sole source of air of combustion for each heater assembly is the intake orifice 17 of the associated branch conduit 12 in the flue 10. Because of the thermal siphon effect of the gas burning at the nozzle of the burner 14, gas is drawn from the flue through the orifice 17, stripped of at least a portion of its oxygen, and discharged at a higher temperature from the discharge orifice 18 of the conduit 12 which is upwardly spaced from the orifice 17.

A throttling valve 20 is arranged in each branch conduit 12 between the intake orifice l7 and the burner- 14. As is better seen in FIG. 2, the valve is similar to the automatic flue damper disclosed and claimed by two of us in US. Pat. No. 3,510,059 in that it has an axially short, cylindrical frame 19 which fits tightly into the conduit 12 and two quadrants 21 of bi-metallic sheet material which, in the illustrated condition of the valve, practically completely block one half of the flow section of the frame 19 and of the conduit 12. The other half 22 is permanently open to provide the proper amount of air of combustion when the flue 10 carries pure air, that is, no lower heater is operating.

The quadrants 21 are provided with spacedly parallel slots 23 which divide each quadrant into individually bendable tongs. When a lower heater operates, the gas reaching a higher heater is a mixture of air and of combustion gases, its oxygen content is lower, and its temperature is higher than that of ambient air. Because of thermal expansion, the oxygen content of each unit volume of the gas reaching the higher burner is further reduced. While much of the gas flows through the opening 22, enough flows around the quadrants 21 and through the slots 23 to raise the temperature of the birnetal and to flex the tongs out of their illustrated position so that they open additional flow paths for the gases in the conduit 12, thereby increasing the oxygen supply to the associated burner 14 in response to the operation of a lower burner to approach an optimal supply.

The bi-metal quadrants 21 are readily selected for proper response to hold the flow section of the associated branch conduit in a desirable range as the number of operating lower burners and the temperature of the gas supplied varies. Obviously, no bi-metal valve is needed in the lowermost heater assembly, not illustrated, and the response characteristics of valves in the higher heater assemblies must be varied in accordance with the number of lower heater assemblies that may be operated simultaneously. There is enough gas turbulence about the tongs of the quadrants quickly to close the throttle valve to the illustrated position in response to the interruption of operation of a lower heater assembly and thereby to decrease the flow section of the branch conduit 12.

While the damper or valve of the earlier patent has been found effective and virtually indestructible in heating installations ofthis invention, other control elements responsive to the temperature of the gas entering the branch conduit 12, bi-metallic or otherwise, may be substituted for the slotted quadrant 21.

When the gas temperature is not sensed by the operating elements of the valve itself, the valve may be located anywhere in the branch conduit 12 if so desired, and the sensing element may be located in the branch conduit ahead of the burner 14 or even in the flue although better correlation with the oxygen content of the supplied air is achieved when the temperature is sensed in the conduit 12 between the orifice l7 and the burner 14.

It should be understood, therefore, that the foregoing disclosure relates only to a preferred embodiment of the invention, and that it is intended to cover all changes and modifications in the example herein chosen for the purpose of the disclosure which do not depart from the spirit and scope of the invention set forth in the appended claims.

What is claimed is:

l. A gas-fired heating installation comprising, in combination:

a. a vertically extending exhaust flue;

b. a first heater assembly and a second heater assem- C. means for supplying air of combustion and a gaseous fuel to said first assembly, said first assembly communicating with a first portion of said exhaust flue for discharge of gases of combustion formed in said heater assembly by combustion of said gaseous fuel into said first portion,

1. said second heater assembly including i. a branch conduit having an intake orifice and an exhaust orifice in a second portion of said flue upwardly spaced from said first portion, ii. a burner in said conduit intermediate said oriiii. supply means for supplying gaseous fuel to said burner, and

iv. flow control means in said conduit for controlling the flow of gas from said intake orifice to said burner,

2. said flow control means including means responsive to operation of said first heater assembly for increasing the flow section of said branch conduit, and responsive to the interruption of operation of said first heater assembly for reducing the flow section of said branch conduit.

2. An installation as set forth in claim 1, wherein said intake orifice constitutes the sole significant source of air of combustion for said second heater assembly.

3. An installation as set forth in claim 2, wherein said discharge orifice is upwardly spaced from said intake orifice.

4. An installation as set forth in claim 2, wherein said flow control means respond to the temperature of the gas entering said branch conduit from said flue through said intake orifice.

5. An installation as set forth in claim 4, wherein said flow control means include a throttling valve movable toward and away from a position in which said valve partially obstructs said branch conduit.

6. An installation as set forth in claim 2, wherein said flow control means include a bi-metallic element in said branch conduit between said intake orifice and said burner in contact with gas flowing in said branch 

1. A gas-fired heating installation comprising, in combination: a. a vertically extending exhaust flue; b. a first heater assembly and a second heater assembly; c. means for supplying air of combustion and a gaseous fuel to said first assembly, said first assembly communicating with a first portion of said exhaust flue for discharge of gases of combustion formed in said heater assembly by combustion of said gaseous fuel into said first portion,
 1. said second heater assembly including i. a branch conduit having an intake orifice and an exhaust orifice in a second portion of said flue upwardly spaced from said first portion, ii. a burner in said conduit intermediate said orifice, iii. supply means for supplying gaseous fuel to said burner, and iv. flow control means in said conduit for controlling the flow of gas from said intake orifice to said burner,
 2. said flow control means including means responsive to operation of said first heater assembly for increasing the flow section of said branch conduit, and responsive to the interruption of operation of said first heater assembly for reducing the flow section of said branch conduit.
 2. said flow control means including means responsive to operation of said first heater assembly for increasing the flow section of said branch conduit, and responsive to the interruption of operation of said first heater assembly for reducing the flow section of said branch conduit.
 2. An installation as set forth in claim 1, wherein said intake orifice constitutes the sole significant source of air of combustion for said second heater assembly.
 3. An installation as set forth in claim 2, wherein said discharge orifice is upwardly spaced from said intake orifice.
 4. An installation as set forth in claim 2, wherein said flow control means respond to the temperature of the gas entering said branch conduit from said flue through said intake orifice.
 5. An installation as set forth in claim 4, wherein said flow control means include a throttling valve movable toward and away from a position in which said valve partially obstructs said branch conduit.
 6. An installation as set forth in claim 2, wherein said flow control means include a bi-metallic element in said branch conduit between said intake orifice and said burner in contact with gas flowing in said branch conduit. 